Ion Transport Behavior in Triblock Copolymer-Templated Ordered Mesoporous Carbons with Different Pore Symmetries

Mesoporous carbons with 3-D body-centered cubic, 2-D hexagonal, and wormlike symmetries were synthesized via organic-organic self-assembly and further activated by CO, to improve the pore connectivity. These samples have almost the same mesopore size but different pore symmetries and connectivity, which are used as the model materials to investigate the ion transport behavior in mesoporous channels by using galvanostatic charge-discharge, cyclic voltametry, and electrochemical impedance spectroscopy. Results show that 2-D hexagonally mesoporous carbon delivers the best capacitance retention and the lowest impedance to electrode kinetic processes. These indicate that the 2-D hexagonal pore symmetry is more favorable for ion diffusion than the isolated 3-D cubic and disordered wormlike pore characteristics. Compared to the pristine mesoporous carbons, the activated samples exhibit remarkable improvement in ion transport ability within the mesopores. The development of micropores makes the separated pore channels interconnect to each other. Such an improved interconnectivity of mesopores is favorable for the ion diffusion process through providing more entrances and shorter distances for electrolyte accessibility, consequently, improving the efficiency of ion transport.